Introduction to luminescence

Light-emitting diodes (LEDs) have taken the world by surprise with its flair and application in almost every field that can come from human imagination. To understand the imperative presence of LEDs in today’s world, it is essential to know the complete journey from the prehistoric period that slowly and gradually led to the development of this outstanding technology. The history of lighting is broadly classified into four generations and LEDs have dominated the fourth and the latest generation of lighting. This chapter takes through the different phases of lighting that started with the burning of firewood and oil lamps, followed by the lamps working on the principles of incandescence, fluorescence, and, finally, the LEDs. Here, the concepts associated with the luminescence phenomenon and its mechanisms are also highlighted.